class Arel::UpdateManager

def group(columns)
  columns.each do |column|
    column = Nodes::SqlLiteral.new(column) if String === column
    column = Nodes::SqlLiteral.new(column.to_s) if Symbol === column
    @ast.groups.push Nodes::Group.new column
  end
  self
end

def having(expr)
  @ast.havings << expr
  self
end

def initialize(table = nil)
  @ast = Nodes::UpdateStatement.new(table)
end

def set(values)
  if String === values
    @ast.values = [values]
  else
    @ast.values = values.map { |column, value|
      Nodes::Assignment.new(
        Nodes::UnqualifiedColumn.new(column),
        value
      )
    }
  end
  self
end

def table(table)
  @ast.relation = table
  self
end